Even the efficient-market theory’s own authors doubted full strong-form efficiency.

Evidence

The third category of “available information” was that to which only certain groups, such as corporate insiders, were privy. If this kind of information was always reflected in prices, and insiders could not make excess profits on the basis of it, a market was “strong form” efficient. “We would not, of course, expect this [strong form] model to be an exact description of reality,” wrote Fama (1970, p. 409), and indeed there was already evidence against it. — Donald MacKenzie, An Engine, Not a Camera, 295

Categorization

• XREF: Contrasts with popular presentations that treat Fama as a dogmatic efficient-market believer; he conceded strong-form failure from the start. — connects to: Modigliani himself distrusted the theorem he co-authored, doubting its assumptions of perfect markets — Donald MacKenzie, An Engine, Not a Camera: How Financial…, 187; Most finance theorists’ own trading contradicted strict market efficiency. — Donald MacKenzie, An Engine, Not a Camera: How Financial…, 1114; Even efficient-market theorists privately acknowledged mispricings existed. — Donald MacKenzie, An Engine, Not a Camera: How Financial…, 1109

Broader Connections

• Even efficient-market theorists privately acknowledged mispricings existed. #corroborates (0.92) — Donald MacKenzie, An Engine, Not a Camera, 1109
• Most finance theorists’ own trading contradicted strict market efficiency. #corroborates (0.80) — Donald MacKenzie, An Engine, Not a Camera, 1114